Put them into some sorta creative small container / package where a kid would have to remove it strategically and they'd sell like hotcakes. Like an egg that breaks apart (think hatchables). Kids go nutz for that kind of shit.

There really isn't a 'cheap' option. It's just 'fucking expensive', and 'really fucking expensive'. I just sculpted a monster for some company. The guy said the molds alone cost him 25 K and to manufacture 100 figures will cost an additional 60K. They look great tho. Just released his Kickstarter today.